Chuck's Home Theater

[chhelo]

First post with my design and build as I go home theater. Overall, it seems I do all my projects this way. Hard to plan everything prior to starting as most the time it results in numerous changes regardless of how well you plan.

I will appreciate any comments as I post ideas and pictures of how the build proceeds. My goal is to have it up and runing in 4 to 6 months. Since my 2 sons are now off to college and home mostly on weekends the gameroom to home theater conversion does not infringe on their desire to dominate the upstairs any longer.

Here we go! Basic Design, Front Wall & Back Wall. Disregard the furniture na dold carpet I have rolled up. Waiting to complete the riser and then have the carpet guy install new carpet.

Building the riser with 2X8's and MDF for the decking. Building with the idea it acts as a bass absorber and tactile feel. The black spacers used to decouple from the floor were made from radiator hose. When you walk on the 2x8's they have a solid feel but still will allow for good response to LF vibrations. Leaving room to add Buttkicker if required.

More later.

[Ethan Winer]

chhelo wrote:

I will appreciate any comments

My main comment now is that people in the second row will not have the surrounds behind them. Not sure if there's a perfect solution for that, and maybe you won't often have people back there. Or it'll be in-laws in which case who cares.

Also, your PDF shows a few "acoustic panels (as required)" and no bass traps. In a room that size bass trapping should be a high priority, and the side wall (and ceiling) reflection points also need to be treated.

--Ethan

[chhelo]

Ethan,

Thanks for the post. Now I know it was a good idea to open this up for comment.

I am basically designing the room so the premier seating is the back row at the 16' listening position. In-laws & kids can set on the front row.

Did not even think to consider placing the surrounds on the rear row of seats. Will relocate the surrounds to that position. One question however, how will this affect the rears and if they will still provide any benefit?

I do have a design for some bass traping and will post the conceptual details when I have them completed. Also, planning on a ceiling panel/absorber in front of the ceiling fan on the screen side.
The riser will have two Helmholtz Resonant Absorber's built in. I need to draw this up and post to see if what I am concepting will work. Also, all of the holes you see cut in the floor are where I blew in 30 bags of cocoon insulation to kill as much sound as possible to the kitchen located below. Between the floor and the ceiling is about 16 inches filled with insulation. The side walls are open to only attic space so I can cut into or do any mods required with little worry on them.

My in-wall equipment bay is located on the left hand wall. It has a glass door that slides open to the left.
See attached photos. I built this several months ago with a home theater in mind. It has a slide out platfom and the brackets to hold equipment also have an extension arm and pivot left or right to allow access to the rear of each piece of equipment. The arms are also adjustable in height. The glass door is mounted to the steel framework by magnets glued to the glass.

Thanks,

Chuck

[Ethan Winer]

Chuck,

> I am basically designing the room so the premier seating is the back row at the 16' listening position. <

If you do that, place the rear seats so your ears are 7.3 feet from the rear wall behind you, or as close to that distance as you can manage. Whatever you do, do not put either row of seats halfway back in the room front to rear. That's where the worst bass null is located. See THIS article on my company's site for more information on seating placement.

> Did not even think to consider placing the surrounds on the rear row of seats. Will relocate the surrounds to that position. One question however, how will this affect the rears and if they will still provide any benefit? <

I have only 5.1, not 7.1, but my understanding is the rear speakers go all the way back on the rear wall.

--Ethan

[Sonnie]

What are the dimensions of the room?

Our room is 19.5' deep. We tried the side surrounds on the front row and as we all might expect, it didn't sound right for the back row. We moved the surrounds to the rear corners and it worked out fine.

[chhelo]

Ethan,

If I place the aft row based on the 38% rule I really have row for one row of seats as the forward row would be at 6 to 7 feet. As you state placing a listening positon at the mid point is not the preferred method but what choice do I have.

Right now if I keep the aft row at 16 feet I am only a little over 3 feet off the back wall. I guess my room dimensions realy are not all that good.

Looks like I will need a lot of bass traping to really kill of all the residual bass.

I am still working on the idea my riser can contain a large amount of bass traping but I may be to new to the world of acoustic design to know what I am really doing.

In the aircraft world when we have to soundproof interiors we rely on lightweight methods. The preferred method is many different materials bonded together to create a blanket that is light as possible to block the transmission of sound. One design we worked on had small internal absorbers imbedded. I need to see if I can locate that file and see if I can recreate cheap enough to make it practical.

Working on the drawing now for the riser mounted absorbers. Should have ready to post this week end.

[chhelo]

Sonnie,

Thanks for the info. I have attached a new revised room layout regarding the same issue. To place the surrounds furhter back or if I use dipoles I can get both rows at one time.

Overall, I am considering completing the riser, having my chairs delivered, then installing the speakers and othe AV equipment. Once I have it up and running then I can move things around and install acoustic devices as required to get the sound I like.

If this is the wrong approach and I need more planning send in the HT Police and have them put me in cuffs.

[Sonnie]

Chuck, I think your room is really kinda small for 7.1. You could try it, but my room is almost the same depth as yours and 7.1 wouldn't work... or didn't sound right... may have just been me, but personally I think 5.1 is going to be your ticket.

I would do this:

[chhelo]

Sonnie,

Thanks for your input. I most likely will start with a 5.1 system as I can always expand later.

Had planned to purchase AV gear for a 7.1 system but speakers are part of the major cost and rears can be added later. Good thing I have the time to experiment and not in a hurry.

The other unique issue that may have revalence is the slanted ceiling's on the left and right side. The question is can speakers be located on the slanted ceiling directed at an angle towards the seating or is this a bad idea. I have not seen this issue addressed anywhere.

Chuck

[Sonnie]

I've seen and installed surrounds on slanted walls and as long as the levels are set properly there were no issues I could discern.